This sounds as if you are trying to get someone to do your homework. Can you give us a little more detail? Before we give you an answer, can you at least give us several possible outcomes of the problem?

I'm not going to explain the whole theory here, but you should know that in this kind of circuit the [tex]V_c[/tex] precedes the current by 90 degrees, [tex]V_L[/tex] is lagging by 90 degrees, and [tex]V_r[/tex] corresponds to the current exactly. (I'm probably using the wrong terms and not explaining this very well ).

Therefore you can draw a diagram of [tex]{V_c}_{max}[/tex], [tex]{V_L}_{max}[/tex], and [tex]{V_r}_{max}[/tex], whereby [tex]{V_c}_{max}[/tex] is 90 degrees ahead of [tex]{V_r}_{max}[/tex] and [tex]{V_L}_{max}[/tex] is 90 degrees behind it.

But you should also know that all the time:

[tex]V_r + V_L + V_c = V_s[/tex]

So to find [tex]V_s[/tex] at any moment you need to sum up all three V's, while treating them as vectors. On the axis that connects [tex]{V_c}_{max}[/tex] and [tex]{V_L}_{max}[/tex] the sum would be [tex]{V_c}_{max} - {V_L}_{max}[/tex], and on the other axis the sum would simply be [tex]{V_r}_{max}[/tex]. Using pythagoras you can show that: